Tabbing machine

ABSTRACT

Apparatus for feeding, welding and cutting metallic ribbon which is extremely thin. The ribbon is advanced by automatic means so that a portion thereof is nested within a slot which forms one electrode of a welding device. The welding operation is performed and then the ribbon is cut to length, the welded parts are then removed and the cycle is repeated. The means for accurately advancing the ribbon comprises a pair of rotatably mounted metallic rollers aligned along a common axis. At least one of the roller assemblies is comprised of first and second concentrically mounted rollers spaced by resilient means. The true centers of the rollers are displaced by a predetermined amount so as to provide constant tension for the feeding operation even in the case where the rollers deviate from true round which may be caused by wearing as a result of continued use.

United States Patent [72] Inventor Jerome Vincent V0111 Union, NJ [21]App]. No. 815,997 [22] Filed Apr. 14, I969 [45] Patented July 27, 1971[73] Assignee Griffiths Electronics Inc.

Linden, NJ.

[S4] TABBING MACHINE 11 Claims, 3 Drawing Figs.

52 U.S.Cl 219/80, 83/580, 226/156, 226/187, 226/191 5| 1111.01 ..B23k11/00 [50] Field o1Search.....- 226/176, 177, 186, 191, 142, 156, 181,190, 194; 83/156, 580; 219/80 [56] References Cited UNITED STATESPATENTS 2,804,968 9/1957 Elliott..... 226/186 3,074,608 1/1963 Ohme226/156 X Primary ExaminerRichard A. Schacher Atromey0strolenk, Faber,Gerb & Soffen ABSTRACT: Apparatus for feeding, welding and cuttingmetallic ribbon which is extremely thin. The ribbon is advanced byautomatic means so that a portion thereof is nested within a slot whichfonns one electrode of a welding device. The welding operation isperformed and then the ribbon is cut to length, the welded parts arethen removed and the cycle is repeated. The means for accuratelyadvancing the ribbon comprises a pair of rotatably mounted metallicrollers aligned along a common axis. At least one of the rollerassemblies is comprised of first and second concentrically mountedrollers spaced by resilient means. The true centers of the rollers aredisplaced by a predetermined amount so as to provide constant tensionfor the feeding operation even in the case where the rollers deviatefrom true round which may be caused by wearing as a result of continueduse.

TABBING MACHINE The present invention relates to feeding, welding andcutting apparatus, and more particularly to novel apparatus foraccurately feeding exact lengths of extremely thin metallic ribbon to awelding station where exact lengths of ribbon may be welded to anothercomponent and then cut to exact size after the weld, wherein theapparatus is designed for continuous repeated use.

There exist a variety of applications wherein it is required torepeatedly perform a particular operation such as in the case of massproduction techniques. For example, in the cathode ray tube art, inorder to fabricate the assemblies utilized in such cathode ray tubes atmass production rates, it becomes necessary to provide equipment forcontinuous repeated performance of certain operations wherein the partsformed and/or joined may be so formed and/or joined rapidly, accuratelyand reliably. For example, in the fabrication of electron gunassemblies, there are a large number of components which must beaccurately positioned and aligned relative to other components. Oncesuch components are so aligned, it then becomes necessary to weld thecomponents in order to provide good mechanical and electrical connectiontherebetween. The electrical connection of many components within theelectron gun is provided for by the welding of extremely thin metallicribbon to such components. The metallic ribbon utilized in theseapplications is extremely thin and thereby necessitates careful handlingin the performance of the welding operations. Since there are numerouswelds required in the fabrication of each cathode ray tube electron gun,and since the number of electron guns being produced is quite large, itbecomes necessary to provide equipment which can perform theseoperations both rapidly and reliably.

The presentinvention is characterized by providing equipment capable ofrapidly feeding extremely thin metallic ribbon to a welding stationwhere, subsequent to the welding operation, parts are accurately cut tolength and the cycle is repeated in a rapid manner without affecting theintegrity of the components being joined.

The present invention is comprised of equipment for automaticallyoperating roller means which, upon actuation, operates to feed anextremely thin metallic ribbon to a welding station wherein the lengthof ribbon fed to the welding station is of an exact predetermined lengthfor each feeding operation. After the weld is produced, the ribbon iscut to a predetermined length, and the cycle is repeated. In order toaccurately and reliably feed exact lengths of the extremely thinmetallic ribbon, the roller advancing means is comprised of a pair ofcooperating rollers which moves or advances the ribbon therebetween. Thecenters of the rollers lie on a common axis and at least one rollerassembly is comprised of a pair of metallic concentric rollers having aring of resilient material therebetween. The centers of the pair ofrollers are displaced toward one another by a predetermined amount inorder to maintain constant tension on the metallic ribbon, even in thecase where the rollers deviate from true round as a result of wear dueto repeated usage. The equipment is designed to perform the advancing,welding and cutting operations in rapid t and accurate fashion, therebylending itself advantageously to mass production techniques.

It is, therefore, one object of the present invention to pro- I videnovel means for advancing, welding and cutting extreme Iy thin metallicribbon repeatedly and continuously, wherein the cut ribbon sectionsfonned in each operation are each of an exact length.

Another object of the present invention is to provide novel means forfeeding extremely thin metallic ribbon to a welding station by means ofa roller assembly wherein the roller assembly includes at least oneresiliently mounted roller displaced inwardly relative to a cooperatingroller so as to maintain constant tension upon the metallic ribbon andaccurately feed predetermined lengths of the ribbon even after wearingof the roller members as a result of repeated usage.

These as well as other objects of the present invention will becomeapparent when reading the accompanying description and drawings inwhich:

FIG. 1 is an elevational view ofa ribbon feeding machine incorporatingthe principles of the present invention.

FIG. 2 is an end view of the ribbon feeding machine of FIG. 1.

FIG. 3 is a perspective view showing a typical electron gun componentwelded to a ribbon section through the use of the method and apparatusof the present invention.

The ribbon-feeding machine 10, as shown in FIGS. 1 and 2, is comprisedof a base or support member 11 which may be mounted upon a platform orother horizontal surface for supporting the machine. An air cylinder 12is secured to base 11 by fastening means 13,13 so as to be rigidlymounted thereto. Although not shown in detail, it should be understoodthat air cylinder 12 is comprised of a hollow, cylindrical bore (notshown) having a piston (not shown) mounted for reciprocal movementtherein. This piston is rigidly secured to a rod 14 whose upper threadedend is, in turn, secured to an arm guide 15. Air cylinder 12 is providedwith first and second openings 12a and 12b for coupling to a suitableair pressure source (or sources, not shown) which operate in a mannersuch that the introduction of air under pressure into opening 12b urgesarm 14 vertically upwardly, as shown by arrow 14a. The termination ofthe introduction of air pressure into opening 12b and the initiation ofthe introduction of air pressure into opening 12a causes arm 14 to movevertically downward, as shown by arrow 14b, to return to the solid lineposition of FIG. 1. This operation serves to advance the metallic ribbonin a manner to be more fully described.

The arm guide 15 is provided with a horizontally aligned slot (notshown) for receiving lever arm 16 which may be rigidly secured to armguide 15 by means of a fastening member 17 threadedly engaging a tappedaperture (not shown) provided in one vertical surface of arm guide 15and bearing against one surface of lever arm 16 to rigidly mechanicallyjoin elements 15 and 16. In this manner, the upward vertical movement ofarm 14 is imparted to lever arm 16 through arm guide 15, causing leverarm 16 to rotate clockwise (relative to FIG. 1) about shaft 17. Arm 16is clamped to shaft 17 by means of a lever clutch clamp assembly 18further secured by fastening means 19. Also rigidly mounted to shaft 17is a gear 20 which is designed to rotate in the clockwise direction(relative to FIG. 1) each time arm 16 rotates about shaft 17 in theclockwise direction. The operation is such that the upward verticalmovement of rod 14 causes arm 16 to pivot in the clockwise directionabout shaft 17. This movement is imparted through shaft 17 to gear 20until the rod 14 moves to its uppermost position. Upon the downwardvertical movement of rod 14, the clutch assembly 18 decouples lever arm16 from shaft 17, imparting no rotation to the shaft and thus holdinggear 20 motionless until the next upward vertical movement of rod 14.

The feed roller housing 21 is comprised of top and bottom plates 22 and23 securedto vertically aligned sideplates 24 and 25 by fastening means26. Housing 21 is secured to a housing support 27 by fastening means 28which passes through an opening in bottom plate 23 and threadedlyengages a tapped aperture provided in the top end of housing support 27.The bottom end of housing support 27 is secured to the baseplate 11 byfastening means 29 which passes through an opening in the base plate andthreadedly engages a tapped opening provided in housing support 27.

The sideplates 24 and 25 rotatably mount a plurality of shafts such as,for example, shaft 17 which is journaled within suitable bearings (notshown) provided within the sideplates. A first roller assembly 30 iscomprised of a shaft 31 journaled within suitable bearings 32 providedin the sideplates 24 and 25 (only one of which are shown in FIG. 2). Thegear member 33 is rigidly secured to shaft 31 so as to rotate in unisontherewith under control of gear 20 in a manner to be more fullydescribed. A lower roller 34 is mounted upon the lefthand end of shaft31 (relative to FIG. 2) and is positioned adjacent the outside face ofsideplate 24. A roller guard 35 is, in turn, mounted against the outsideface of roller 34 and is held in position by fastening means 36.

The upper roller assembly is comprised of a shaft 37 journaled withinthe bearings 38 and 39 provided in sideplates 24 and 25, respectively.The upper roller assembly 40 is comprised of an inner roller 41 rigidlysecured to shaft 37, an outer roller 42 and a pair of resilient O-rings43 and 44 positioned between the outer periphery of roller 41 and theinner periphery of roller 42. The entire roller assembly 40 is securedto shaft 37 by a pair of nuts 45 and 46. A gear 47 is rigidly secured toshaft 37 and meshes with gear 33 mounted on shaft 31 to operate in amanner to be more fully described.

A slip clutch 48 is mounted to shaft 31 and is provided for holdingroller 34 motionless during the return stroke of rod 14 in a manner tobe more fully described. A support 49 for shaft 31 is fastened to bottomplate 23 by fastening means 50 for securing the clutch clamp and byfastening means 51 for securing the bracket of slip clutch 48.

The extremely thin metallic ribbon is wound about the ribbon feed roller52 positioned to rotate counterclockwise, as shown by arrow 53, aboutits center shaft 54. The ribbon is fed from the bottom of the feedroller toward the right where it is maintained in alignment within aplate having a ribbon feed guide 55. The ribbon then passes between theouter surfaces of roller 42 and roller 34 and within a slot provided asa front guide 56 for the ribbon in member 57 which is integrally joinedto shaft support plate 49. The ribbon then passes through a cutter 57 sothat its forward end may nest within a slot provided in one electrode 58of a welding unit. The other electrode 59 is positioned immediatelyabove electrode 58 so that its tapered lower end is positioned directlyabove the ribbon 60. The electrodes, when electrically energized, weldthe ribbon section to a second member (at location 770.) so as to formthe subassembly shown in FIG. 3.

The cutting operation is controlled by an electrically operated solenoidassembly 61 having a coil 62 mounted upon solenoid support 63 which, inturn, is rigidly secured to base member 11. The solenoid selectivelyoperates an armature 64 coupled to a cutter wedge arm 65 linked toarmature 64 by a pin 66. The forward end of cutter wedge arm 65 ismechanically coupled to a cutter wedge 67 by a fastening pin (not shown)passing through openings in the bifurcated portions 65a and 65b of arm65 and embracing the left-hand end of cutter wedge 67, which openingsare in alignment for receipt of the fastening pin, as shown by thenumeral 68 in FIG. 1. Armature 64 is based by suitable means (not shown)so as to be normally in the solid line position of FIG. 1 when thesolenoid coil 62 is deenergized. Upon energization of the solenoid coilby a switch, foot pedal or other suitable means, armature 64 is movedtoward the left, as shown by arrow 69, causing the cutting wedge 67 tomove in the left-hand direction. The inclined surface 670 of cutterwedge 67 bears against a similarly inclined surface 70a provided alongthe underside of cutter body 70.

The cutter body 70 is provided with an elongated, rectangular-shapedopening 71 through which cutter guide 57 passes. The lower portion ofcutter guide 57 is coupled to cutter support 71 by means of a couplingpin 72 which is passed through suitable openings 73a and 73b in thebifurcated portions 74a and 74b of cutter support 71, and through asuitable opening 57a provided in cutter guide 57 which is in alignmentwith openings 73a and 73b. Cutter guide 57 is provided with arectangular-shaped slot 57b near its upper end. Ribbon 60 passes throughslot 57b while being moved into the slot provided in welding electrode58 into which it is nested in readiness for the welding operation. Thecutting edge of cutter body 70 is located at 70b and operates in amanner to be more fully described hereinbelow.

The operation of the feeding, welding and cutting equipment is asfollows:

Let it be assumed that the extremely thin metallic ribbon has been fedto the slot in electrode 58 where it is nested in readiness for thewelding operation. The welding unit 75 mounted adjacent the feeding andcutting machine 10 by a suitable support 76, is energized, causing alarge electrical potential to appear across the welding electrodes 58and 59 to weld the forward end of ribbon 60 to a grid member 77, thewelded elements being shown in final assembled form in FIG. 3.

After completion of the welding operation which joins element 60 and 77,solenoid coil 62 is energized, causing its armature 64 to move in thedirection shown by arrow 69 against a biasing force provided by a springor other suitable means (not shown). This movement causes cutting wedge67 likewise to move in the direction shown by arrow 69. its inclinedsurface 671: bears against surface a of cutter body 70, causing thecutter body to move vertically upward in the direction shown by arrow78. Cutter wedge 67 is bifurcated and cutter guide 57 passes between thebifurcated arm portions so as to experience no vertical movement duringthe sliding movement of cutting wedge 67 and the upward verticalmovement of cutter body 70. The cutting edge 70b makes slidingengagement with the righthand vertical surface of cutter guide 57,passing through the ribbon 60 at point 79 and moving slightly above theright-hand end of slot 57b so as to cleanly cut the right-handmostsection of ribbon 60 from the remaining ribbon being fed through themechanism from feed roller 52.

The deenergization of solenoid coil 62 causes its armature 64 to bemoved in the right-hand direction, as shown by arrow 80, under controlof the biasing means provided therein. This causes cutting wedge 67 tomove to the solid line position shown in FIG. 1, thereby allowing thecutter body 70 to move vertically downward and return to the solid lineposition of FIG. 1.

The two welded components 60 and 77 are removed from the welding unitand air cylinder assembly 12 is activated by the injection of airpressure into opening 12a, causing rod 14 to move vertically downward,as shown by arrow 14b. This movement is imparted to lever arm 16,causing the arm 16, shaft 17 and gear 20 to rotate in thecounterclockwise direction about the axis of shaft 17. Thiscounterclockwise rotation is imparted to gear 33 which meshes with gear20, causing gear33 to rotate in the clockwise direction, as shown byarrow 82. Gear 33 also meshes with gear 47, causing this gear to rotatein the counterclockwise direction, as shown by arrow 83. The ribbon 60which passes between the roller 34 and roller assembly 40 is therebyadvanced to be fed in the direction shown by arrow 84 so as to be movedinto the slot provided in welding electrode 58 in readiness for the nextwelding operation. A very significant feature of the ribbonfeedingassembly resides in the fact that constant tension is maintained betweenthe roller assemblies and hence upon the metallic ribbon passingtherebetween, by the arrangement of the roller assemblies. As shown bestin FlG. l, the centers of roller 34 and roller assembly 40 are alignedalong a common vertical axis represented by the phantom line 85. Thedistance between the centers of roller 34 and roller assembly 40 isequal to the center-to-center mounting distance between the rollers whenjust touching one another minus a finite distance which, in onepreferred embodiment, is 0.010 inch. By displacing the center-to-centermounting distances by this small amount, constant tension is maintainedtherebetween. This slightly offcenter mounting is absorbed by theresilient 0"- rings 43 and 44 which act to maintain the proper tensionand cause the ribbon to be fed by an accurate amount, in spite ofwearing of the outer roller 42 and roller 34 which may occur as a resultof continued use. This arrangement has been found to be capable offeeding, in the preferred embodiment, the extremely thin metallic ribbon(which, in the preferred embodiment, has a thickness of 0.002 inch and awidth of 0.06 inch) by exactly 11/16 of an inch each time the aircylinder is ac tivated to feed the ribbon.

After advancing of the ribbon 60 in the manner described hereinabove,air pressure is released from opening 12a in the cylinder and injectedinto opening 12b to cause the connecting rod 14, arm guide 15 and leverarm 16 to be moved vertically upward and return to the starting positionshown in solid line fashion in FIG. 1. During this movement, the slipclutch assembly 18 mounted between arm 16 and shaft 17 decouples theclockwise rotation of arm 16 about shaft 17 from shaft 17, preventingthe rotation of gear 20. Concurrently with this operation, the slipclutch assembly 48 mounted to shaft 31 further restrains roller 34 fromexperiencing any movement in the counterclockwise direction (relative toFIG. 1) to thereby hold roller 34 and roller assembly 40 motionlessuntil the next advancing operation.

The above cycle is then repeated by a welding operation and a subsequentcutting operation. The welding, cutting and ribbon feeding operationsmay be rapidly repeated as frequently as necessary in order to join theassociated electron gun pats.

Whereas the description of the preferred embodiment teaches the weldingof a ribbon section to electron gun part 77, it should be understoodthat ribbon sections of differing lengths and thicknesses may be fed,welded and cut in a similar manner and be joined to other components, ifdesired, simply by providing a suitable supporting mount for the machinepart to which the ribbon is to be joined.

It can be seen from the foregoing description that the present inventionprovides a novel automatic method for rapidly and accurately feedingextremely thin metallic ribbon and cutting the ribbon to exactpredetermined lengths as rapidly and as frequently as is necessary.Rapid, accurate advancement of the extremely thin metallic ribbon isaccomplished through the use of a metallic roller assembly in which thecenter-to-center mounting distance of the rollers is displaced by apredetermined amount to maintain constant tension upon the ribbon beingfed and to accurately advance the ribbon in a repeated fashion, even inthe case where slight wearing of the rollers may occur due to long,repeated use as a result of the provision of resilient means between theinner and outer rollers of the upper roller assembly.

Although this invention has been described with respect to particularembodiments, it should be understood that many variations andmodifications will now be obvious to those skilled in the art, and,therefore, the scope of this invention is limited not by the specificdisclosure herein, but only by the appended claims.

What I claim is:

1. Means for advancing an extremely thin metallic ribbon comprising:

a thin elongated metallic ribbon;

a first rotatably mounted roller assembly;

a second rotatably mounted roller assembly;

the centers of rotation of said first and second assemblies lying alongan imaginary straight line;

each of said first and second roller assemblies including a firstmetallic roller arranged to make rolling engagement with one another:

means coupled to both said first and second roller assemblies forrotating said assemblies in opposing rotational directions to feed saidribbon therebetween;

said first roller assembly further comprising resilient means positionedabout the center of rotation of said first roller assembly and withinthe interior of its associated metallic roller;

means for urging said roller assemblies toward one another to maintainconstant tension on said ribbon for accurate feeding of the ribbontherebetween, said first roller assembly being further comprised ofinner and outer concentric metallic rollers mounted to rotatesubstantially about the common center of rotation of said firstassembly, said resilient means comprising first and second resilientO-rings arranged in spaced parallel fashion and surrounding the outerperiphery of said inner roller and engaging the inner periphery of saidouter roller. 2. The device of claim 1 wherein said rotating meanscomprises means for intermittently rotating both said first and secondroller assemblies so as to intermittently feed said ribbon.

3. The device of claim 1 wherein said rotating means comprises:

a first shaft;

a lever arm having a first end secured to said first shaft and beingmounted to rotate said lever arm and said first shaft about the axis ofsaid first shaft;

a first gear mounted upon said first shaft;

means for reciprocally moving the free end of said lever arm;

slip clutch means coupled between said lever arm and said first shaftfor coupling said lever arm to said shaft when said lever arm is movedin a first direction and for decoupling said first shaft from said leverarm when said lever arm is moved in the opposite direction.

4. The device of claim 3 wherein said first and second roller assembliesare further respectively comprised of second and third gears forrotating their associated roller assemblies;

said second gear being adapted to mesh with said first and third gearsso as to rotate said first and second roller assemblies when said firstgear is rotated.

5. The device of claim 4 further comprising second slip clutch meanscoupled between said second gear and the first roller of said secondroller assembly to restrain said first and second roller assemblies fromrotating when said lever arm is moving in said opposite direction.

6. The device of claim 1 further comprising means for cutting saidribbon after being fed through said roller assemblies.

7. The device of claim 1 further comprising a cutter guide positioned atthe outfeed end of said roller assemblies and having an opening forreceiving said ribbon whereby said ribbon passes through said opening asit is fed by said roller assemblies;

a reciprocating cutter member arranged to slide across one end of saidopening;

means for moving said cutter member in a first direction across saidopening when energized and for moving said cutter member in seconddirection away from said opening when deenergized.

8. The device of claim 1 further comprising a welding assemblypositioned at the outfeed end of said roller assemblies, said weldingassembly being comprised of first and second electrodes adapted to welda portion of said ribbon to an associated part;

at least one of said electrodes having a slot positioned to receive andsupport the free end of said ribbon fed thereto to facilitate thewelding operation.

9. The device of claim 8 further comprising means for cutting the weldedsection of the ribbon positioned between said welding assembly and theoutfeed end of said roller assemblies to separate the welded ribbonsection from the remainder of said elongated ribbon.

10. The device of claim 1 wherein the distance between the centers ofrotation of said first and second roller assemblies is equal to theradius of the outer roller of said first roller assembly plus the radiusof the second roller assembly minus a finite length in the range from0.005 to 0.015 inch.

11. The device of claim 1 wherein the distance between the centers ofrotation of said first and second roller assemblies is equal to theradius of the outer roller of said first roller assembly plus the radiusof the second roller assembly minus a finite length in the range from0.005 to 0.015 inch and is preferably 0.010 inch.

1. Means for advancing an extremely thin metallic ribbon comprising: athin elongated metallic ribbon; a first rotatably mounted rollerassembly; a second rotatably mounted roller assembly; the centers ofrotation of said first and second assemblies lying along an imaginarystraight line; each of said first and second roller assemblies includinga first metallic roller arranged to make rolling engagement with oneanother: means coupled to both said first and second roller assembliesfor rotating said assemblies in opposing rotational directions to feedsaid ribbon therebetween; said first roller assembly further comprisingresilient means positioned about the center of rotation of said firstroller assembly and within the interior of its associated metallicroller; means for urging said roller assemblies toward one another tomaintain constant tension on said ribbon for accurate feeding of theribbon therebetween, said first roller assembly being further comprisedof inner and outer concentric metallic rollers mounted to rotatesubstantially about the common center of rotation of said firstassembly, said resilient means comprising first and second resilient''''O''''-rings arranged in spaced parallel fashion and surrounding theouter periphery of said inner roller and engaging the inner periphery ofsaid outer roller.
 2. The device of claim 1 wherein said rotating meanscomprises means for intermittently rotating both said first and secondroller assemblies so as to intermittently feed said ribbon.
 3. Thedevice of claim 1 wherein said rotating means comprises: a first shaft;a lever arm having a first end secured to said first shaft and beingmounted to rotate said lever arm and said first shaft about the axis ofsaid first shaft; a first gear mounted upon said first shaft; means forreciprocally moving the free end of said lever arm; slip clutch meanscoupled between said lever arm and said first shaft for coupling saidlever arm to said shaft when said lever arm is moved in a firstdirection and for decoupling said first shaft from said lever arm whensaid lever arm is moved in the opposite direction.
 4. The device ofclaim 3 wherein said first and second roller assemblies are furtherrespectively comprised of second and third gears for rotating theirassociated roller assemblies; said second gear being adapted to meshwith said first and third gears so as to rotate said first and secondroller assemblies when said first gear is rotated.
 5. The device ofclaim 4 further comprising second slip clutch means coupled between saidsecond gear and the first roller of said second roller assembly torestrain said first and second roller assemblies from rotating when saidlever arm is moving in said opposite direction.
 6. The device of claim 1further comprising means for cutting said ribbon after being fed throughsaid roller assemblies.
 7. The device of claim 1 further comprising acutter guide positioned at the outfeed end of said roller assemblies andhaving an opening for receiving said ribbon Whereby said ribbon passesthrough said opening as it is fed by said roller assemblies; areciprocating cutter member arranged to slide across one end of saidopening; means for moving said cutter member in a first direction acrosssaid opening when energized and for moving said cutter member in seconddirection away from said opening when deenergized.
 8. The device ofclaim 1 further comprising a welding assembly positioned at the outfeedend of said roller assemblies, said welding assembly being comprised offirst and second electrodes adapted to weld a portion of said ribbon toan associated part; at least one of said electrodes having a slotpositioned to receive and support the free end of said ribbon fedthereto to facilitate the welding operation.
 9. The device of claim 8further comprising means for cutting the welded section of the ribbonpositioned between said welding assembly and the outfeed end of saidroller assemblies to separate the welded ribbon section from theremainder of said elongated ribbon.
 10. The device of claim 1 whereinthe distance between the centers of rotation of said first and secondroller assemblies is equal to the radius of the outer roller of saidfirst roller assembly plus the radius of the second roller assemblyminus a finite length in the range from 0.005 to 0.015 inch.
 11. Thedevice of claim 1 wherein the distance between the centers of rotationof said first and second roller assemblies is equal to the radius of theouter roller of said first roller assembly plus the radius of the secondroller assembly minus a finite length in the range from 0.005 to 0.015inch and is preferably 0.010 inch.